IS FLUCTUATION CONDUCTIVITY A PROBE TO DETERMINE THE PRESENCE OF S OR D -WAVE PAIRING IN HIGH-T_C SUPERCONDUCTORS?

摘要

Can the fluctuation conductivity(or paraconductivity) be used as an experimental probe for the detection of s or non-s wave (d wave?) pairing in high temperature superconductors? As it can be shown Maki - Thompson effect turns out to be absent for pure d-wave superconductors. In other words, the scattering of the electrons to impurities has the effect of destroying the pairing, if this is not of the s-wave kind, since the out-coming electrons do not satisfy any more the pairing relation in the momentum space. Thus, the presence or absence of Maki - Thompson terms in the fluctuation conductivity of a high T_c superconducting sample can be used to determine the presence or absence of s-wave pairing. Experimental results concerning fluctuation measurements on different superconductors are presented.